Steroidal hormones of natural origin for the most part have not one, but a variety of biological activities. Steroid research has been directed towards finding more active and more specific hormones. The approach usually followed has been to modify the natural steroidal nucleus by addition of substituents or by variation of the side-chain. A different type of modification is planned in the present research and the overall project is designed to prepare a wide variety of steroids and sesquiterpenes possessing hormonal and antitumor activity. The approach followed will be based upon a total synthesis pattern. The proposed steroidal research has as its basis the preparation of the fusidic acid and shionone tetracyclic ring systems which occur in the biogenetic sequence between squalene and cholesterol. These nuclei will be prepared by total synthesis and the materials related to natural hormones will be tested for biological activity. The proposed sesquiterpenes research has as its basis the synthesis of compounds related to the antitumor lactone, vernolepin. The general eudalene nucleus possessing the requisite functions will be prepared and a structure activity relationship in the sesquiterpene lactone series will be obtained.